Train A and train B are running on parallel tracks in the opposite directions with speeds of 36 km/hour and 72 km/hour, respectively. A person is walking in train A in the direction opposite to its motion with a speed of 1.8 km/hour. Speed (in ms−1) of this person as observed from train B will be close to: (take the distance between the tracks as negligible)
a. 29.5 ms^-1
b. 28.5 ms^-1
c. 31.5 ms^-1
d. 30.5 ms^-1